During this new lockdown I’ve found the time for reading again the paper by Vondrak, Capitaine and Wallace describing a long term model for precession and started to translate the fortran code published into Pascal. Their article is publicly available at https://www.aanda.org/articles/aa/pdf/2011/10/aa17274-11.pdf
Previously I did several tests with P03 model, throughout the whole period of time covered by the DE431 ( 13000 BCE to 17000 CE) using as a reference the software SOLEX12 by Prof. Aldo Vitagliano (http://www.solexorb.it) and I wasn’t completely satisfied with the result obtained by P03 model for epochs far more than 8000 years from J2000, in both directions. That convinced me to adopt what I call the “Vondrak Matrix” that swept away the preceding models used by Uruk_One.
That said, let’s see what I’ve done so far:
- FTP download of “astorb.dat” has now a better control over the connection.
- The solar eclipses canon now covers all the DE431 time span.
- The Asteroids Grid has now the column of the object name fixed. It doesn’t scroll anymore.
- In the Asteroid Grid added a new column containing the elongation from Sun.
- Bug: Right Ascension sometimes showed seconds as “60.0”. Solved.
- Added the LBT Telescope (Mount Graham) to the location file.
- Bug : Code cleaning caused a wrong computation of the geocentric ecliptic coordinates of planets. Solved.
- Bug: Nutation computed on stars had an error of 0.5s in RA due to a typo into the formula. Solved.
- Vondrak Precession Model substitutes P03 and VSOP87 models.
- Mean obliquity of the Ecliptic is obtained by the above new precession model.
- Bug: the projection used by the All Sky Map is now correctly shown into the Preference Window.
- Added a new window with some info about Planets. (see Image below)
13. In the HOR View Grid the Local Meridian is highlighted with a thicker line.
14. From now on the user can input dates and JDNs in UTC as well (someone will say: eventually!). Events saved so far will keep correctly the date (TDT of course) but it will be erroneously shown as UTC. Switch the selection to TDT, press the button to update the engine and save the Event again. This should solve the problem. This is not a small change, the risk that some bug will come out is real, so there’s a lot to test here.
15. Modified and added some info for tracked Planets, Stars and DSO.
So respectively from top to bottom we have: - Observed Altitude - Azimuth (NESW) - Visual Magnitude - Refraction applied to the tracked object - Dip of the Horizon (depends on the Observer's Altitude over the sea level) - Atmospheric Extinction (from 0.2 for Zenithal Distance = 0 to 10 for Zenithal Distance approx. equal to 90°)
Hi
First of all Happy New Year and my best wishes for the future developments of Uruk_One.
The new improvements to come up look very interesting.
Regarding Vondrak et al. long term model of precession published in 2011, there is also an erratum published in 2012 : https://www.aanda.org/articles/aa/full_html/2012/05/aa17274e-11/aa17274e-11.html
JPL HORIZONS still use DE431 and will switch to DE441 in the coming days (the ascii files are available but when all downloaded = 8.88 Go !) : it will be interesting to compute the differences DE431 vs DE441 for ancient times.
All the best
Hi,
firstly thanks for the wishes that I gladly reciprocate to you. Yes,I was aware of the erratum, a periodic term was wrong. I’m still waiting that the official documentation (already approved by the platform) will be out before proceeding. Actually I’m more interested with the DE441, that is the older ephemeris in terms of updates. Don’t worry about disk space, I will translate all files into binary, gaining with performance and saving a lot of disk space.
Stay safe,
Alberto